A former deputy governor of China's southern province of Hainan has been sentenced to 12 years in prison for corruption, the official Xinhua news agency said on Wednesday.

Ji Wenlin was a one-time ally of Zhou Yongkang, the country's once-powerful domestic security boss, who was felled by President Xi Jinping's anti-corruption campaign.

Xi has warned that rampant corruption threatens the survival of the ruling Communist Party and has waged a war on graft in the past three years that has swept up scores of senior officials in the party, the government, the military and state-owned companies.

Investigators began looking into Ji's activities as early as 2014, Xinhua said, adding that he used his position to seek benefits, including investments for several companies, illegally obtaining 20.4 million yuan (£2.2 million)in assets and bribes.

Ji's official biography says he worked under Zhou when the latter was the party boss of the southwestern Sichuan province and the public security minister, among other posts. Zhou was jailed for life last June.

Several key Zhou allies have been ensnared in the anti-graft campaign, including Jiang Jiemin, the former top regulator of state-owned assets.